Common warmth retention materials available from the market include primarily natural flocculus (including cotton, wool, feather, and the like) and synthetic flocculus (primarily synthetic fiber flocculus). The principle of warmth retention of such flocculus is to retain still air as more as possible thereby preventing or isolating the flow of heat. Accordingly, a warmth retention material is required to have, or to be form as, a fluffy structure.
A warmth retention material comprises a phase change material incorporated therein to achieve temperature regulation of the object that is kept warm, wherein the phase change material may be distributed on the top and bottom surfaces of the warmth retention material, or entered the same with a decreasing gradient. On one hand, a high content of the phase change material results in a good temperature regulating effect, but it may make the warmth material harder in hand feeling. Meanwhile, the thickness of the material would also decrease, which would affect the filling power of the same. On the other hand, in order to impart wash resistance, the phase change material is typically applied to, or retained within the warmth retention material by dipping, or drawing and stretching in combination with surface spray coating and secured by hydroentangling, needle punching, or the like. These processes for incorporating a phase change material and securing the warmth retention material, i.e. dipping, drawing, hydroentangling and needle punching, would make the warmth retention material become dense and thinner, and the filling power of the same would decrease and the hand feeling would be harder as compared with the warmth retention material that is not incorporated with the phase change material. Therefore, when this warmth retention material is used in garments, bedding articles, it needs to be improved. Chinese patent application publication CN 102561027 A discloses a flocculus with smart temperature regulating function and a method for preparing the same. According to the description, a flocculus with smart temperature regulating function is formed by combination of a phase change material and a flocculus substrate by padding, soaking for water absorption, spray coating and sprinkling, spray coating, among others, wherein the method comprises mixing the stock fibers, carding the mixed fibers, lapping to form a fiber web, drawing and stretching the fiber web, and spray coating onto both surfaces of the fiber web with a mixture solution of the phase change material and an adhesive.
Chinese patent application publication CN 102587150 A discloses a method of producing an energy storage nonwoven fabric fiberfill. According to the description, the method comprises (by following the basic manufacturing process of a melt-blown non-woven fabric): using a high polymer raw material for producing the non-woven fabric as the principal raw material and mixing a phase change microcapsule with a UV curable resin in a certain ratio; spray coating the mixture onto the surfaces of the thin non-woven layer; curing; placing the resulting non-woven fabric on web forming curtain; repeating blowing decomposition to thicken the non-woven fabric; and securing by hydroentangling, needle punching, heat punching, and the like to form the energy storage nonwoven fabric fiberfill.
Apparently, with respect to such warmth retention materials, there are still some problems in incorporating sufficient phase change material into a warmth retention material and keeping it securely therein, and thus providing a desired temperature regulating performance and wash resistance, as well as retaining a sufficient filling power and good hand feeling, and such problems need to be addressed.